The present invention generally relates to negatively charged membranes, and in particular to negatively charged membranes comprising a porous substrate and a crosslinked coating. The membranes find use in the treatment of fluids containing positively charged species such as proteins, e.g., in ion-exchange chromatography.
Negatively charged ion-exchange membranes have been proposed for the separation and/or purification of biomolecules such as proteins, amino acids, and nucleic acids. For the ion exchange membrane to perform effectively in the above applications, the membrane should satisfy several important parameters. For example, the membrane should exhibit high rates of fluid flow. The membrane should have high dynamic binding capacity for biomolecules, and should be capable of selectively binding the biomolecules, which have different surface charges. The membrane should, therefore, have low non-specific binding, e.g., resulting from hydrophobic interactions. The membrane should withstand high treatment fluid velocities. The preparation of the membrane should not involve chemistries and processes that are cumbersome to practice. Some of the cation exchange membranes known heretofore suffer from the failure to satisfy one or more of the parameters set forth above.
Accordingly, there exists a need for a cation exchange membrane that exhibits high rates of fluid flow. There further exists a need for a cation exchange membrane that has high dynamic binding capacity and selectivity for biomolecules. There further exists a need for a membrane that has low non-specific binding or low binding that results from hydrophobic interactions. There further exists a need for a membrane that can withstand high fluid flow velocities. There further exists a need for a membrane that involves preparation chemistries and/or processes that are not cumbersome to practice.
These advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
U.S. Pat. No. 5,021,160 discloses copolymers synthesized from 2-acrylamido-2-methyl-1-propane sulfonic acid and either N-(isobutoxymethyl)acrylamide or 2-hydroxyethyl methacrylate and a process for preparing anionic charge modified microporous filtration membranes.
WO 98/17377 discloses charged membranes comprising a porous substrate and a cross-linked polyelectrolyte or hydrogel located in the pores of the substrate.
European Patent Application No. 0 474 617 A1 discloses a surface modified support membrane wherein the support membrane has a layer of hydrogel deposited on the surface thereof.